GRAND JUNCTION, Colo. Snowmobiler Caleb Moore remains in critical condition in a Colorado hospital after a dramatic crash at the Winter X Games in Aspen.

Moore's grandfather told The Denver Post the prognosis isn't good and that it's "almost certain" the 25-year-old won't recover.

A family spokeswoman reissued a statement Tuesday thanking fans, friends and family for their support and asked for continued prayers. They declined further comment.

Moore was performing a flip Thursday when he clipped the top of a jump and went over the handlebars. The snowmobile rolled over him, but he walked off with help and went to a hospital with a concussion.

He later developed bleeding around his heart and was flown to Grand Junction for surgery. His family said Sunday that Moore then had a secondary complication involving his brain.

Moore, a veteran at racing and jumping ATV four-wheelers, won a freestyle bronze medal at the X Games in both 2010 and 2011, according to The Denver Post.